<s>
The	O
Zenit	O
trademark	O
is	O
associated	O
with	O
35	O
mm	O
SLR	B-Algorithm
cameras	I-Algorithm
.	O
</s>
<s>
Among	O
related	O
brands	O
are	O
Zorki	B-Algorithm
for	O
35mm	O
rangefinder	B-Algorithm
cameras	I-Algorithm
,	O
Moskva	O
(	O
Moscow	O
)	O
and	O
Iskra	O
for	O
medium-format	O
folding	O
cameras	O
and	O
Horizon	B-Algorithm
for	O
panoramic	O
cameras	O
.	O
</s>
<s>
The	O
early	O
Zorki-based	O
models	O
before	O
that	O
time	O
were	O
labelled	O
"	O
Zenith	O
"	O
in	O
a	O
handwritten	O
style	O
of	O
script	O
.	O
</s>
<s>
The	O
above	O
Zenit	O
was	O
based	O
on	O
the	O
Zorki	B-Algorithm
rangefinder	B-Algorithm
camera	I-Algorithm
(	O
a	O
copy	O
of	O
the	O
Leica	O
II	O
)	O
.	O
</s>
<s>
In	O
transforming	O
the	O
Zorki	B-Algorithm
into	O
an	O
SLR	B-Algorithm
,	O
the	O
simplest	O
approach	O
was	O
taken	O
:	O
the	O
rangefinder	B-Algorithm
housing	O
was	O
removed	O
from	O
the	O
top	O
and	O
replaced	O
by	O
a	O
plain	O
ground-glass	O
screen	O
and	O
prism	O
;	O
a	O
mirror	O
was	O
added	O
below	O
with	O
a	O
lever	O
operated	O
mirror	O
setting	O
system	O
and	O
the	O
M39×1	O
thread	O
mount	O
was	O
pushed	O
forward	O
to	O
make	O
room	O
for	O
the	O
mirror	O
inside	O
.	O
</s>
<s>
During	O
the	O
first	O
years	O
of	O
production	O
(	O
until	O
the	O
Zenit-E	O
of	O
1967	O
)	O
Zenit	O
camera	O
development	O
coincided	O
with	O
that	O
of	O
the	O
Zorki	B-Algorithm
cameras	O
.	O
</s>
<s>
The	O
Zenit-S	O
had	O
PC-synchro	O
for	O
external	O
flash	O
units	O
(	O
almost	O
like	O
the	O
Zorki-S	O
)	O
and	O
the	O
Zenit-3M	O
also	O
had	O
an	O
RF-sibling	O
,	O
the	O
Zorki-6	O
.	O
</s>
<s>
For	O
an	O
SLR	B-Algorithm
,	O
the	O
Pentaprism	O
of	O
all	O
classical	O
Zenits	O
was	O
undersize	O
,	O
with	O
the	O
viewfinder	O
showing	O
about	O
two-thirds	O
of	O
the	O
actual	O
frame-size	O
.	O
</s>
<s>
Camera	O
production	O
switched	O
to	O
the	O
M42×1	B-Algorithm
thread	O
(	O
also	O
known	O
as	O
Praktica	O
thread	O
)	O
and	O
an	O
instant-return	O
mirror	O
was	O
also	O
developed	O
.	O
</s>
<s>
Production	O
included	O
both	O
M39×1	O
and	O
M42×1	B-Algorithm
mounts	O
for	O
the	O
Zenit	O
E	O
and	O
Zenit	B-Algorithm
B	I-Algorithm
models	O
.	O
</s>
<s>
Later	O
models	O
were	O
only	O
produced	O
in	O
the	O
M42×1	B-Algorithm
with	O
the	O
Pentax	B-Algorithm
K	I-Algorithm
mount	I-Algorithm
available	O
for	O
the	O
latest	O
models	O
.	O
</s>
<s>
The	O
poor	O
durability	O
and	O
high	O
manufacturing	O
cost	O
of	O
this	O
concept	O
in	O
contrast	O
to	O
the	O
classical	O
barebone	O
Zenit	O
design	O
based	O
on	O
ultimate	O
simplicity	O
showed	O
KMZ	O
to	O
have	O
taken	O
a	O
wrong	O
track	O
:	O
Nevertheless	O
,	O
the	O
Zenit-5	O
was	O
the	O
first	O
Soviet	O
motor-driven	O
SLR	B-Algorithm
camera	I-Algorithm
,	O
and	O
the	O
first	O
Soviet	O
zoom	O
lens	O
(	O
Rubin-1c	O
2.8/37	O
–	O
80	O
,	O
based	O
on	O
Voigtländer	O
Zoomar	O
design	O
)	O
featured	O
in	O
the	O
Zenit-6	O
.	O
</s>
<s>
This	O
was	O
a	O
camera	O
with	O
an	O
original	O
electromagnet-driven	O
focal-plane	O
shutter	O
,	O
M42	B-Algorithm
lens	I-Algorithm
mount	I-Algorithm
,	O
and	O
shutter	O
speeds	O
from	O
1	O
sec	O
to	O
1/1000	O
.	O
</s>
<s>
The	O
Zenit-19	O
was	O
,	O
perhaps	O
,	O
the	O
top-of-the-line	O
Soviet	O
M42	B-Algorithm
lens	I-Algorithm
mount	I-Algorithm
camera	O
.	O
</s>
<s>
This	O
had	O
a	O
Pentax	B-Algorithm
K	I-Algorithm
mount	I-Algorithm
(	O
which	O
was	O
proposed	O
as	O
an	O
open	O
standard	O
by	O
Pentax	B-Application
and	O
distributed	O
freely	O
)	O
and	O
a	O
focal	O
shutter	O
with	O
horizontal-travel	O
cloth	O
curtains	O
.	O
</s>
<s>
The	O
only	O
operation	O
mode	O
was	O
aperture-priority	B-Algorithm
.	O
</s>
<s>
Its	O
distinguishing	O
feature	O
was	O
the	O
introduction	O
of	O
a	O
manual	O
shutter	O
mode	O
in	O
addition	O
to	O
aperture-priority	B-Algorithm
.	O
</s>
<s>
This	O
is	O
the	O
second	O
microprocessor-controlled	O
camera	O
in	O
the	O
Zenit	O
range	O
(	O
the	O
first	O
one	O
was	O
the	O
second	O
variant	O
of	O
the	O
Zenit-automat	O
camera	O
)	O
,	O
and	O
the	O
second	O
(	O
after	O
the	O
Zenit-5	O
)	O
motor-driven	O
SLR	B-Algorithm
camera	I-Algorithm
built	O
by	O
KMZ	O
.	O
</s>
<s>
X-sync	O
is	O
1/125	O
sec	O
,	O
and	O
the	O
camera	O
includes	O
both	O
manual	O
shutter	O
and	O
aperture-priority	B-Algorithm
modes	O
as	O
well	O
as	O
DX-coding	O
from	O
50	O
to	O
3200	O
ISO	O
.	O
</s>
<s>
The	O
Zenit-KM	O
Plus	O
was	O
the	O
final	O
Zenit	O
camera	O
to	O
be	O
produced	O
;	O
all	O
SLR	B-Algorithm
camera	I-Algorithm
production	O
at	O
the	O
Krasnogorsk	O
factory	O
ceased	O
.	O
</s>
<s>
These	O
highly	O
interesting	O
ultimate	O
Zeniths	O
would	O
have	O
been	O
major	O
sellers	O
on	O
Western	O
markets	O
during	O
the	O
"	O
SLR-decade	O
"	O
of	O
the	O
1970s	O
.	O
</s>
